The present invention relates to a cold HC emission controlling device for use in automobiles equipped with a catalytic type disposal system.
It is well known that automobiles are equipped with so-called catalytic type disposal system as a measure for reducing the emission of noxious exhaust emmissions, particularly for reducing total HC during the engine operation.
However, this system has a drawback that the desired activity of the catalyst is not obtained until the catalyst temperature is raised to a predetermined level by the exhaust gas. To obviate this problem, various countermeasures have been proposed. One of the proposed techniques is to generate unburnt substances at the time of cold start after an engine-off period to promote a rise of the temperature of the catalyst. These countermeasures, however, have not been successful.
It is also known to provide a so-called deceleration emission controlling device having a dash pot or throttle positioner for controlling the total HC emission at the time of deceleration or gear shifting. This controlling device also has a drawback that it inconveniently increases the rate of fuel consumption. In addition, the drivability of the engine is liable to be deteriorated. For instance, engine braking is rendered less effective.